Re: [PATCH v3] eal: fix unaligned loads/stores in rte_memcpy_generic

[Stephen Hemminger <stephen@networkplumber.org>]

On Sun, 16 Jan 2022 09:33:19 -0500
Luc Pelletier <lucp.at.work@gmail.com> wrote:

> As a side note, and to follow up on Stephen's indication that this is
> 'performance critical code', I think it might be worthwhile to
> revisit/revalidate the current implementation of rte_memcpy. There's a
> good thread here that mentions rte_memcpy, and its performance on at
> least one platform/architecture combination is far from being the
> best:
> 
> https://github.com/microsoft/mimalloc/issues/201
> 
> It seems like enhanced rep movsb could be faster on more recent CPUs,
> but that's currently not being used in the current implementation of
> rte_memcpy.
> 
> I understand some of this may not be directly related to this patch,
> but whoever looks at this patch might want to provide their thoughts
> on whether updating rte_memcpy would be worthwhile? I suspect looking
> at all current public implementations of memcpy (libc, microsoft,
> compilers builtin implementations, etc.) might help in making
> improvements.

I would prefer that rte_memcpy did not exist at all.
Instead the system library should always be used.

It is only exists because some architectures have slower code
in glibc.